Structure Sensitivity in the Partial Oxidation of Styrene, Styrene Oxide, and Phenylacetaldehyde on Silver Single Crystals

The partial oxidation of styrene, styrene oxide, and phenylacetaldehyde were investigated on the Ag(110) surface by temperature-programmed reaction spectroscopy. The reactions of these species appear to proceed through the oxametallacycle intermediate. In contrast to the formation of styrene oxide observed on Ag(111) and Ag(100), the production of styrene oxide from the oxametallacycle via ring closure is clearly inhibited on the Ag(110) surface. The competing reaction pathways following the formation of the oxametallacycle lead to the production of phenylacetaldehyde (545 K), phenylketene (550 K), benzene (600−605 K), benzoic acid (590 K), and phenylacetic acid (600 K). Phenylacetaldehyde and phenylketene are formed via C−H bond activation, while benzoic acid and phenylacetic acid are derived via the nucleophilic attack of oxygen atoms at the electron-deficient carbonyl carbon. These results have important implications for catalytic partial oxidation of olefins by silver-based catalysts.